1. Field of the Invention
The present invention relates in general to a caption video cassette recorder (VCR), and more particularly to a caption VCR having a caption decoder, therein, for detecting a caption signal from a broadcasting signal or detecting the caption signal recorded on a VCR tape and to a method of displaying the caption signal from the caption decoder together with an audio signal and a video signal in the caption VCR.
2. Description of the Relevant Art
For the purpose of further display of a caption signal in a VCR in which an audio signal and a video signal are displayed, a deaf person or a foreign language learner usually detects the caption signal from a broadcasting signal containing the caption signal or detects the caption signal recorded on a VCR tape, utilizing a separate, external caption decoder. Then, the detected caption signal from the caption decoder is displayed together with the audio and video signals in the VCR.
With reference to FIG. 1, there is shown a block diagram of a conventional on-screen display apparatus for a VCR. The illustrated circuit comprises a programmable controller 31 for providing a plurality of control signals necessary to the VCR in accordance with a selection of the user, a radio frequency (RF) converter 32 for receiving an external broadcasting signal through a receiving antenna ANT1 and outputting a desired signal through a transmitting antenna ANT2 under a control of the programmable controller 31, a tuner 33 for tuning the broadcasting signal from the RF converter 32 to a broadcasting channel required by the user under a control of the programmable controller 31, demodulating the tuned broadcasting signal to divide it into a video signal and an audio signal AU and outputting the divided video signal and audio signal AU, a switching circuit 34 for selectively outputting one of the video signal from the tuner 33 and an external video signal under a control of the programmable controller 31, a luminance/chrominance (Y/C) processing circuit 35 for video-processing an output signal from the switching circuit 34 or a self-video signal to be played back under a control of the programmable controller 31, an on-screen display unit 36 for displaying an output signal from the Y/C processing circuit 35 and an external caption signal under a control of the programmable controller 31, a buffer 37 for buffering an output signal from the on-screen display unit 36 and outputting the buffered signal through the RF converter 32 and through a video output jack VOJ externally, and a separate caption decoder 38 for detecting the caption signal from the broadcasting signal or the caption signal recorded on a VCR tape and the detected caption signal to the on-screen display unit 36.
The operation of the on-screen display apparatus for the VCR with the above-mentioned construction will now be described.
The programmable controller 31 provides a plurality of control signals necessary to the VCR in accordance with the selection of the user.
The radio frequency (RF) converter 32 receives the external broadcasting signal through the receiving antenna ANT1 and transmits the received broadcasting signal to the tuner 33. Also, the RF converter 32 outputs a desired signal through the transmitting antenna ANT2 in accordance with a control signal TV/VCR from the programmable controller 31. Namely, in a television (TV) mode, the RF converter 32 outputs the broadcasting signal inputted through the receiving antenna ANT1 directly through the transmitting antenna ANT2 externally, otherwise, in a VCR mode, the RF converter 32 modulates the video signal and caption signal from the buffer 37 to a broadcasting frequency required by the user and outputs the modulated video signal and caption signal through the transmitting antenna ANT2.
The tuner 33 tunes the broadcasting signal from the RF converter 32 to a broadcasting channel required by the user in accordance with a control signal D1 from the programmable controller 31, demodulates the tuned broadcasting signal to divide it into the video signal and the audio signal AU and outputs the divided video signal and audio signal AU. Then, the audio signal AU is transferred to an audio processing circuit (not shown) and the video signal is transferred to the switching circuit 34.
The switching circuit 34 selectively outputs one of the video signal from the tuner 33 and an external video signal through a video input jack VIJ to the Y/C processing circuit 35 in accordance with a control signal Tuner/Line from the programmable controller 31. Namely, in a Tuner mode, the switching circuit 34 outputs the video signal from the tuner 33, otherwise, in a Line mode, the switching circuit 34 outputs the external video signal inputted through a video input jack VIJ.
The Y/C processing circuit 35 video-processes the output signal from the switching circuit 34 or a self-video signal to be played back in accordance with a control signal W/EE from the programmable controller 31 . Namely, in a W mode, the Y/C processing circuit 35 outputs the self-video signal to be played back. Otherwise, in an EE mode, the Y/C processing circuit 35 outputs the output signal from the switching circuit 34.
The on-screen display unit 36 displays the output signal from the Y/C processing circuit 35 and the caption signal from the separate caption decoder 38 in accordance with a control signal D2 from the programmable controller 31. Namely, upon an enable slate of the control signal D2 from the programmable controller 31 , the on-screen display unit 36 displays the output signal from the Y/C processing circuit 35. At this time, if the caption signal is applied from the separate caption decoder 38 during the display of the video signal from the Y/C processing circuit 35, the on-screen display unit 36 stops displaying the video signal from the Y/C processing circuit 35 and displays the caption signal from the separate caption decoder 38. Then, if no further caption signal is applied from the separate caption decoder 38, the on-screen display unit 36 displays the video signal from the Y/C processing circuit 35 again. On the other hand, upon a disable state of the control signal D2 from the programmable controller 31, the on-screen display unit 36 outputs the output signal from the Y/C processing circuit 35 and the caption signal from the separate caption decoder 38 to the buffer 37.
Herein, the broadcasting signal may mean a character multiplex broadcasting signal containing video, audio and caption signals. Also, the video signal from the Y/C processing circuit 35 may contain the caption signal. However, in the conventional VCR, the caption signal cannot be detected from the video signal from the Y/C processing circuit 35 without the separate caption decoder 38.
Therefore, in this manner, the caption signal from the separate caption decoder 38 is displayed together with the video signal and audio signal.
On the other hand, upon receiving the video signal and caption signal from the on-screen display unit 36, the buffer 37 buffers the received video signal and caption signal and then sends the buffered video signal and caption signal to the RF converter 32 and also outputs them through the video output jack VOJ externally.
However, the conventional VCR with the above-mentioned on-screen display apparatus has a disadvantage, in that the caption decoder must be installed on the outside of the VCR, separately from the on-screen display apparatus, in order to detect the caption signal from the broadcasting signal, or character multiplex broadcasting signal, or the caption signal recorded on the VCR tape. For this reason, the deaf person or foreign language learner can not help purchasing the caption decoder separately and connecting the separate caption decoder to the VCR, so as to watch a desired image containing the caption on the screen. Therefore, it is inconvenient for the deaf person or foreign language learner to watch a desired image containing the caption signal on the screen utilizing the separate caption decoder.